I think Paul was referring to G-10, which is a fiberglass sheet product. The sheet is cut to shape and can be glued using gorilla glue directly to the framework and replaces the traditional balsa and glass finish. It gives a ready to paint surface. One source is FliteSkin. You can also find generic G-10 too. I've seen it as thin as .005", but for skinning wings, I would go with the .010". It will not conform to compound curves as a single sheet. If you did have compound curves, you would have to strip cover, or use relief cuts.
Here's a horizontal stab covered with the .010 G-10
Here's a turtledeck covered with G-10. gorilla glue on the open structure, and contact cement was used for the ply sides. If memory serves me correctly, this was the .005"
This shows the sharp trailing edges you can get. In this case, the G-10 was applied as a skin on top of a solid balsa core using contact cement.
Here's the painted result of the plane in the second and third photo. It was painted with automotive poly paints and clear coated with MinWax water base poly gloss. The wing was balsa sheeted and glassed the traditional way, but the ailerons were also covered with the .005" G-10
ACP Composites has a great selection and the best prices I've seen.
http://www.acpsales.com/Solid-Fiberglass-Sheets.html
Scott